"According to the label, a British Cadbury Dairy Milk bar contains milk, sugar, cocoa mass, cocoa butter, vegetable fat and emulsifiers," Severson wrote. The Hershey version, on the other hand, lists sugar as its first ingredient. Its list also includes "lactose and the emulsifier soy lecithin, which keeps the cocoa butter from separating from the cocoa."

Tony Bilsborough, a spokesman for Cadbury, told Severson that Cadbury ships to Hershey's Pennsylvania factories a special mix of mashed dried milk, chocolate, and cocoa butter. Hershey takes it from there.

"I imagine [the taste comes] down to the final processing and the blending," Bilsborough told The New York Times.